High selectively polymeric adsorbent based on the hydrogen bonding interaction and the use thereof in isolation and purification of active components from gingko biloba extract

Abstract

Provided are a kind of high selectivity polymeric adsorbents with amide functional groups based on the hydrogen bonding interaction, which is prepared by adequately swelling a DVB-co-MA copolymer of 6% crosslinking degree as the initial resin with dimethyl formamide, performing an amination reaction by adding a diamine, soaking the dried resultant yellow resin with an acylating agent that is a dianhydride, and performing an acylation reaction to obtain the polymeric adsorbent with amide functional groups of the invention. The polymeric adsorbent of the invention can be used to effectively isolate and purify the active ingredients, i.e., flavones and lactones, from the extract of ginkgo leaf.

The invention claimed is: 
     
       1. A high selectivity polymeric adsorbent with amide functional groups based on the hydrogen bonding interaction represented by the following formula: 
       
         
           
           
               
               
           
         
         wherein, n=2˜6, m=0˜4 and the initial resin matrix is a DVB-co-MA copolymer of 6% crosslinking degree and the DVB-co-MA copolymer is in a spheric shape and has a particle size of 0.3˜1.0 mm, an average pore size of 10˜30 nm and a porosity of 50˜65%. 
       
     
     
       2. A method for synthesizing the polymeric adsorbent according  claim 1 , characterized in that the method comprises the following steps:
 first, as the initial resin, the DVB-co-MA copolymer with 6% crosslinking degree is dried sufficiently and put into a 3-neck flask, and then adequately swelled with N,N-dimethyl formamide; a diamine that is 50˜200% of the weight of the initial resin is added as an amination agent, and the reaction is carried out for 8˜12h at a temperature of 60˜140° C.; after the reaction is finished, the reaction mixture is left to stand for cooling down to the room temperature, filtered and washed to give a yellow resin, wherein the reaction process is represented by the following scheme: 
 
       
         
           
           
               
               
           
         
         second, after dried, the yellow resin prepared by the above process is sufficiently soaked with an acylating agent of dianhydride in a 3-neck flask, wherein the amount of the dianhydride is 2˜5 times of the weight of the yellow resin; and then the reaction temperature is raised up to 70˜100° C. and the reaction is maintained for 7˜10h; after the reaction is finished, the reaction mixture is left to stand for cooling down to the room temperature, filtered and washed to obtain the present polymeric adsorbent with amide functional groups, the reaction process is represented by the following scheme: 
       
       
         
           
           
               
               
           
         
         the polymeric adsorbent is numbered as Pnm, wherein n=2˜6, m=0˜4, and the DVB-co-MA copolymer is in a spheric shape and has a particle size of 0.3˜1.0 mm, an average pore size of 10˜30 nm and a porosity of 50˜65%. 
       
     
     
       3. A method of isolating flavones and lactones from ginkgo biloda crude extract, the method comprising the following steps:
 dissolving a commercial ginkgo biloda extract containing flavones of 24˜26% and lactones 6˜6.5% in an aqueous solution of ethanol/water (6:94˜10:90 (V/V) to prepare an adsorption solution with a concentration of 5˜8 mg extract/ml; 
 packing the polymeric adsorbent of  claim 1  into an adsorption column having a ratio of diameter to length of 1:5˜1:20; 
 passing the adsorption solution through the adsorption column at a flow rate of 0.5˜1.0 BV/h at room temperature, wherein the adsorption capacity of the polymeric adsorbent is 1 ml adsorption solution/ml wet adsorbent; and after adsorption, flavones are maintained in the adsorption column by adsorbed by the polymeric adsorbent, while lactones flow out of the adsorption column since they have insufficient adsorption bonding force with the polymeric adsorbent and thus can not be adsorbed by the polymeric adsorbent; and 
 collecting, evaporating and vacuum-drying the effluent to obtain a white solid, wherein the content of lactones is 30˜50 wt % and flavones is not detectable by HPLC detection; 
 eluting the polymeric adsorbent with an aqueous solution of ethanol/water (60:40˜80:20, v/v) at a desorption rate of 0.5˜1.0 BV/h; and 
 recovering ethanol in the eluate through vacuum distillation, and vacuum-drying the residue to obtain a light yellow solid, wherein the content of flavones is 30˜50 wt % and lactones is not detectable by HPLC detection.